Selector switch



Aug. 30,1927. 1,640385 E. O. \NALKER SELECTOR SWITCH Original Filed May 11, 1923' IZ77JEH U Ed'mrz U. h alksr' Patented Aug. 30, 1927.

UNITED STATES PATENT OFFICE.-

. will be assumed that calling subscriber EDWIN O. WALKER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY ASSIGNMENTS, TO 7 AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- V WARE.

SELECTOR swI'rcH.

Application filed ma '11, 1923, S eria1 no... 638,152] Renewed January 20. 1.926.

The present invention. relates in general to selector switches for automatic telephone systems, but is especially concerned with improved circuit arrangements for use in controlling the trunk or automatic selecting operation of automatic switches of the step by step type usually used in automatic telephone systems; and the objectof the invention is to provide controlling circuits wh ch enable the trunk or automatic selectmg Operation of such switches to take place at amaximum speed, while maintaining the present degree of accuracy of operation so essential to the, success of automatic telephone systems.

In order to/illuetrate the invention it will be assumed thatthe well. known ,Strowger switch structure is to be used, althoughit should be understood that the invention may be equally well incorporated in any type of step by step switch.

In the drawing, comprising but a single sheet, Fig. 1 showsja circuit diagram of a selector wired in accordance. with the invention; while Figs. 2 and 3 show modifications which may be substituted for certain of the controlling circuits of Fig. 1.

Referring to Fig. 1, theslector as has its conductors 20, 21 and 22 terminating in bank contacts of any approved type of trunk selecting switch, and is adapted to be controlled. over the conductors 20 and 22 by operating impulses transmitted by a calling.

subscriber in well known manner to position the wipers 23, 2 4 and 25 opposite a des1red group ofbank contacts from which extend trunk lines terminating in other selector or connector switches, depending upon the capacity of the system.

Since Figs. 2 and 3 merely show modifications of certain of the controlling circuits of Fig. 1, a detailed description of these figures will be postponed until a. detalled description of Fig. 1 has been g1ven, after which the application of the modificatlons will be more easily made. clear.

Now in order 'to explain the invention it operating circuit of the release magnet 7, to

shown wishes to extend a connection in an auto: matic telephone system which switches such as that shown inFig. 1 are used. Upon removal of the receiver at the calling station the individual line or trunk selecting switch seizes an outgoing selector switch. Assuming the selector seized to be the one shown in Fig. 1, a circ'uitwill be completed for the line relay 2. This circuit may be traced from ground, lower winding of relay 2", resting contact of armature and said armature, conductor 22, bank contact 12, thru the lower conductor of the line switch (not shown) out over the calling line equipment,through the upper conductor of the line switch, (not shown) bank contact 10, trunk conductor 20 armature 26 and its resting contact, and the upper winding of the line relay 2 to battery. 'The operation of line relay'2 completes a circuit for the release relay 4t, whic'h'also operatesto ground the release trunk 21, to open a point in the close a point in'the operating. circuit of the rotary magnet 5, and to prepare an operating circuit for the usual series relay 6, and vertical magnet 3. The calling subscriber now operates his calling device in accordance with the first digit of the desired'number. A series of interruptions is thereby produced in the circuitof line relay 2, causing a corresponding series of deenergizations of the said relay, which at each deenergization sends a current impulse thru the slow acting relay 6 and the vertical magnet 3 to battery. By

the operation of the vertical magnet the :45

switch shaft is raised step by step until the wipers 23, 24 and '25 stand opposite the bank level in which are terminated the particular group oft-runk lines desired. As previous ly stated these trunks may extend to second we selectors or to connectors depending upon the capacity. of the exchange. The slow acting relay 6 is energized in series with the vertical magnet, retaining its armature at tractedthroughout the vertical movement ot the switch. and upon the first Vertical step the off normal springs 14 close a point in the operating circuit of the switching thru relay 8. At the end of the vertical movement of the switch the slow relay 6 restores its armature, which causes a momentary circuit to be completed for the rotary magnet 5. This circuit may be traced from the grounded release trunk conductor 21, oil normal springs 14, armature of relay 6 and its working contact, thru the break spring 29, and the winding of the rotary magnet to battery. This circuit of course is of only momenta ry duration, as it is opened as soon as the relay 6 has fully retracted its armature, but is of sufiicient duration to permit the rotary magnet to close a locking circuit for itself at its springs 17, which are closed at the beginning of the stroke of the arma ture. This locking circuit is maintained until the. rotary magnet has rotated the shaft one step, to position the wipers 28, 2a and 25 on the first bank contacts of the selected group, at which time the locking circuit is broken at interrupter springs 16. opened 7 near the end of the stroke, and the rotary magnet retract-s its armature. The rotary magnet, in restoring its armature, necessarily again closes the locking circuit at interrupter springs 16 before opening the locking springs 17, but the spring used for restoring the armature of the rotary magnet is adjusted so stiff that when the circuit is opened at interrupter springs 16. the reston ing action of the armature is sufiiciently fast to insure its complete retraction and the opening of the locking springs 17 before the magnet has time to again become saturated by the circuit closed through the interrupter springs. The operation now depends upon whether the test contact with which the test wiper 2 1 is'in engagement is busy or is not busy. It the test contact is busy it will have a ground potential upon it, and a circuit will again be completed for operating the rotary magnet. This circuit may be traced from a grounded busy contact such as 32, wiper 2 1, armature 15 and its resting contact, armature 39 and its working contact, interrupter springslti and the winding of magnet 5 to battery. It will be clear that as long as the wiper 24 engages grounded or busy bank contacts that the rotary magnet will continue to vibrate, and at each energization will lock itself up at springs 17 until its wipers have entirely disengaged them selves from the bank contacts of a busy trunk and have been positioned on the subsequent bank contacts to be tested, at which time interrupter contacts 16 will be opened. It will be noted that when the slow acting relay 6 retracted its armature to close the initial operating circuit of the rotary magnet. that ground was also extended from the release trunk conductor 21, thru off normal springs 14, armature ot relay 6 and its resting contact to the winding of switch ing thru relay 8. Flll'tlll'ldOl'O when the rotary magnet 5 energized italso extended ground from its armature 17 and its working Contact to the opposite terminal ol' the winding of relay 8. it will be seen therefore that this relay is always short circuited while the wipers are being moved from one set of contacts to another, and by the grormded or busy test contact while the magnet is deei'iergizing. If however the wiper 24: is positioned on a test contactot' an idle trunk, as soon as the locking circuit is broken at springs 17 there will be no ground present on this Contact, and the s\ itching thru relay will no longer be shortcircuited. This relay will now energize over a circuit extending from battery, winding oi magnet 5, interrupter springs 16, winding of the switching relay 8, resting contact and armature o't slow clay 6, oil normal springs 1 1 to the grounded release trunk conductor 21. Owing to the high resistance of the switchr relay 8, the rotary magnet is not encred by current flow in the above circuit. Relay 8 upon energizing, disconnects the trunk conductors 2t) and 21 from the windings of the line relay 2 and extends them by way of armatures 26 and 27 and their working contacts, line wipers 28 and 25, bank contacts 31 and 33 to the extended idle trunk conductors 3 1 and 36. The deenergization of line relay 2 opens the circuit 01 slow release relay 1, but before this relay retracts its aru'iature to remove ground from the release trunk 21, relays in the switch ahead have operated in well known manner to teed holding ground back over (fUlHlllCtOl 35, bank contact 32, wiper 2 11, armature l5 and its working contact. to the winding ot relay 8, and also back thru springs 1 1 to conductor 21 to maintain ground on the holding circuit of the subscribers lino switch (not shown) as is the usual practice.

' Therelease ot' the selector is brought about in the usual manner, that the calling subscriber upon replacing his receiver causes ground to be removed from conductor SE3 whereupon the switching relay 9 deenergizzes and closes a circuit for the release magnet 7 at armature 28. It should be noted that the rotary magnet is disconnected from the private wiper 24 a armature 39 during the restoringmovement so that it will not be affected by busy contacts engaged at this time. hen the switch s fully restored the release circuit is opened at ott normal springs 9.

The description of the operation oi the selector as shown in Fig. 1 having been completed, the operation of the modification of the rotary magnet controlling circuit shown in 2 will now be described. It should be noted that in the modifications where Sill ill)

group selection is concerned. However,with

the circuits modified, when the switch takes one step in its group selecting movement, the off normal springs 1 1" close, completing a circuit for the slow relay 18, from ground,

windingotrelay 18, working-contact and armature or relay 6 (this relay being energized in series wlth the vertical magnet in the manner previously described)-ofii normal springs 14, and the winding of rotary magnetbto battery. .The relay 18 will energize to apply ground to the resting contact of the armature of relay 6 and to interrupter springs 16 for purposes which will besubsequently made clear. Owing to. the high resistance of relay 18, the rotary, magnet is not energized by current flow in the above circuit. i

At theend of the vertical movement of the switch the slow acting series relay 6 will deenergize, and in so doing opens the energizing circuit of slow release relay 18. An initial operating circuit for the rotary magnet 5 is now completed. This circuit extends from grounded working contact and armature of relay 18, resting contact and armature of relay 6, oil normal springs 14', and the winding of the rotary magnet to battery. The magnet 5 operates to position the wipers corresponding to'wipers 23, 2e

and into engagement with the first contacts of the selected trunk group. The ad justment'of the slow relay 18 may be such that the circuit of magnet '5 is maintained by it, either, only until the locking springs 17 are closed, or until the magnethas been fully operated, in effect the resultant operation will be the same. Assuming the first trunk of the group to-bebusy, as soon as the interrupter and locking springs 16' and 17 of magnet 5' restorea new operating circuit will be completed, from the grounded wiper 24', armature 15 and its resting contact, armature 39 and its working contact, interrupter springs 16, resting contact and armature ot relay 6, off normal springsl and the winding ofthe rotary mag-net- 5' to battery. From this point on the rotary novement of the wipers cor-responding to wipers 23, 24:, and 25 and the switching thru on the first idle trunk is substantially the same aspreviously'described."

It will now be assumed that the selector of Fig. 1 is equipped with a rotary magnet controllingcircuit as shown in the modification Fig. In this modification instead of using a slow relay, such as the relay'18, for

completing the initial operating circuit of the rotary magnet, a pair ofrotary ofil normal springs 13 are used. 1 5

As soon as the vertical magnet gets its first operating impulse the slow relay 6 opens a point in the operating circuit oi the rotary magnet, and as soon asthe switch has taken one complete vertical step a point in the rotary'magnet circuit is closed by OH normal springs 14?. a At the end of the vertical, or group selecting movement of the switch relayfi deenergizesi and completes an initial operating circuit for the rotary magnet 5 from grounded release trunk conduct-or 21 rotary ofl' normal springs 13, armature 39 of relay i and its working contact, armature of relay 6 and its resting contact, interrupter springs 16 vertical off normal springs 14?, and the winding of the rotary magnet- 5 to battery. As soonvas the rotary magnet has taken complete step to properly position the wipers 23, 24 and 25on the bankcontactsjof the first :trunlrot the selected group-the rotary 01f normal springs are opened. The subsequent operating circuit of magnet 5 extends from wiper 24 armature 15 and its resting contact, armature 39 and its working contact, armature of relay 6 and its resting contact, interrupter. springs 16?, vertical ofl' normal springs, 14?, and. the winding of the rotary magnet 5 to battery. .The remainder of the operation is substantially the same-as previously described and therefore need not be repeated; a i i i Having described the invention, what is considered to be new and is desired to have protectedby Letters Patent will be pointed out in the appended claims.

' What is claimed is: I

1.111 an automatic switch, a. stepping magnet, a, plurality of operating-circuits for said magnet, a locking circuit for said magnet, means for closing one of said operating circuits to cause the initial energization said magnet, means responsive to a partial energization of said magnet for closing said lockingcircui-t, means responsive to the complete energization of said magnet for openlng said locking circuit to 'deenergize said magnet, and-means effective onlyatter said locking circuit hasbeen opened for completing a second operation circuit for said magnet to continue the stepping action of the magnet.

' 2. In an automatic switch having wipers wipers into engagement with any set of said bank contacts, an energizing circuit for said magnet to initiate the wiper positioning movement of said magnet, a locking circuit for said magnet closed in response to a partial energization thereof to insure the proper posit oning oisaid wipers independent oi"? iii if u

said first operating circuit, and means for opening said locking circuit after said wipers have been properly positioned.

3. In an automatic hunting switch, a stepping magnet, a test wiper, a circuit for said magnet including said wiper, a self looking circuit for said magnet closed at the beginning of the energization thereof, and contacts for opening both circuits as soon as the magnet is fully energized.

4L. In an automatic hunting switch, a stepping magnet, a test wiper, an armature on said magnet for advancing said wiper when the same is attracted, a circuit for said magnet including said wiper, a locking circuit for said magnet exclu ding said wiper, means controlled by said armature for closing said locking circuit at the beginning of the n1ovement of the armature, and means for opening both circuits when the armature is fully attracted.

5. In an automatic switch, wipers, sets of bank contacts accessible to said wipers, a magnet for moving said wipers into successive engagement with said. sets of bank contacts, an initial energizing circuit for said magnet, a locking circuit for said magnet, means for closing said first circuit for initially operating said magnet to cause said wipers to be moved into engagement with one set of said bank contacts, means for closing said locking circuit until the wipers have been accurately positioned on said set of contacts, and another operating circuit including one of said wipers and a bank contact for initiating the reoperation of said magnet.

6. In a selector switch, primary and secondary operating l'nagnets, a change-over" relay energized in circuit with said primary magnet, contacts on said relay effective when the same deenergizes for transmitting a momentary impulse to said secondary magnet to partially energize the same, and a locking circuit for completely energizing said secondary magnet.

T. In a selector switch, primary and secondary operating magnets. a change-over relay energizcd in circuit with said primary magnet, contacts on said relay effective when the same dcenergizes for transmitting a mo-- mentalimpulse to said secondary magnet to partially energize the same, cont-acts operated by said. secondary magnet responsive to its partial energization. and a circuit including said last mentioned contacts for fully energizing said secondary magnet.

8. In combination, an electromagnet having two circuits, means for partially operating said magnet over the first circuit to close the second circuit, means responsive to a further operation of said magnet for restoring said magnet, and means moved in astep by step manner by successive operations of said magnet.

9. In combination, an electromagnet carrying a vibratory armature, a pair of contacts opened by said armature when it reaches its normal position, a second pair of contacts opened by said magnet armature when it reaches its operated position, and a circuit for said magnet through said two pairs of contacts in series.

10. In combination, an electromagnet carrying a vibratory armature, a pair of contacts operated by said armature when it reaches its normal position, a second pair of contacts operated by said armature when it reaches its operated position, a circuit for said magnet controlled jointly by said two pairs of contacts, and another circuit for said magnet including one pair of contacts and excluding the other pair.

11. In combination, an electromagnet carrying a vibratory armature, a pair of contacts opened by said armature when it reaches its normal position, a second pair of contacts opened by said magnet armature when it reaches its operated position, a circuit for said magnet through said two pairs or contacts in series, and another circuit for said magnet including the second pair of cont acts and excluding the first pair of contacts.

12. In combination, an electromagnet carrying an armature, a pair oi contacts open when said armature is in its normal position, a second pair of contacts opened by said magnet armature in its operated position, a circuit for said magnet controlled jointly by said two pairs of contacts, and an initial energizing circuit for said magnet controlled by only one pair of said contacts.

13. The combination with an aulomatic switch having stepping magnet operated directly through a test wiper, of means made effective by a. partial operation of said stepping magnet through said test wiper for fully operating said magnet independent ot said test wiper and means made effective by full operation of said stepping magnet for bringing about its restoration.

14. In combination, an .electromagnct, means moved in a step by step manner from one position to another position by successive o erations of said magnet, means for establishing an operating circuit for said magnet, and means controlled by said magnet upon its initial energization to first complete a locking circuit for itself and then to cause the deenergization of the magnet.

15. In combination, an electromagnet, means moved in a step by step manner from one position to another position by successive onerationsof said magnet, means for partially energizing said magnet, and means controlled by said magnet as soon as it becomes partially energized to first fully energize the same and then to deenergize it.

16. In an electrical control system wherein there is provided an electroraagnt and magnet becomes partially energized to first fully energize the magnet and then to deenergize it. p

In Witness whereof, I hereunto subscribe my name this 7th day of May, A. 1)., 1923.

EDWIN o. WALKER. 

